1. Field
This invention relates to a system of storing stacks of lumber under compressive force to avoid or correct warpage. In more detail, the system includes providing several open frameworks for use in compressing regular or irregular stacks of lumber. The frameworks are spaced at predetermined distances apart depending on the condition of the lumber being stored.
2. State of the Art
In the past, lumber is generally shipped in stacks and held tightly bound by metals straps or ribbon that encircle the stack of lumber. In this fashion, the metal straps tend to retain newly milled lumber in a flat or un-warped condition. Once the stack of lumber is in storage by the retailer, the metal straps are removed to accommodate sales to customers and no retention force is provided to the stacks of regular or irregular seasoned or unseasoned lumber. Thus, the lumber making up the stacks is subjected to the environment without the metal bands surrounding it thus permitting warpage to some extent.
U.S. Pat. No. 3,831,511, issued to Carl Back, describes an apparatus for delivering lumber though a compressing mechanism by conventional conveyor for moving the lumber into the mechanism and another conveyor for moving the lumber out of the mechanism. The lumber is compressed in a vertical direction by a pressing beam being lowered to contact the upper surface of a bundle of lumber and then a second pressing beam being moved upwardly from underneath to compress the lumber. A third pressing beam moves in the horizontal direction to engage the lumber bundle with the lumber being compressed. A binding device operates to put a band around the lumber while it is under compression. As needed, more than one band may be applied by moving the lumber bundles through the compressing mechanism in several stages where a band or metal strip is applied at each stage. It is apparent such a technique is only successful in avoidance or correction of lumber warpage while the bands or metals strips remain in place.
U.S. Pat. No. 4,220,094 issued to a Ronald Hetherington describes a trimmer machine for trimming lumber packages. Primarily the trimmer is used for trimming packaged lumber to standard lengths without removing metal bands or the like, which are the usual packaging arrangement for shipment of lumber bundles.